I have spent a lot of time in all parts of south Texas and into northern Mexico and haven't ever seen an obsoleta dead or alive. As common as obsoleta is in its normal Texas range and as conspicuous as they are as roadkills, I think if they occurred near the Texas border we would have a lot of specimens.

I would be skeptical of extralimital dots on maps as well because obsoleta is a snake that would be easily transported in firewood and other materials.

Those photos of the bullsnake planted a seed in my mind about bullsnakes vs obsoleta. Clearly obsoleta and guttata/emoryi can coexist and do over most of their range. But it seems that bullsnakes and obsoleta don't overlap in range/habitat very much. In parts of TX where obsoleta occur, P. catenifer don't (or are rare) and vice versa. Maybe it is competitive exclusion between those two species?-----Chris Harrison
San Antonio, Texas